Hydraulic turbine with increased power capacities

ABSTRACT

A hydraulic turbine with increased power capacities for new or existing hydroelectric installations. The turbine has a larger axial runner wheel and a reshaped runner ring peripherally extending around the runner wheel. A draft tube with a larger elbow section extends on a downstream side of the runner ring. A water supply port extends around a rotation axis of the runner wheel on an upstream side of the runner ring, and is adapted to produce a centripetal water flow swirling around the rotation axis of the runner wheel. A turning passageway extends between the water supply port and the runner ring, and is adapted to guide and redirect the centripetal water flow in a substantially axial direction of the runner wheel. An axial distributor extends between the turning passageway and the runner ring.

FIELD OF THE INVENTION

The present invention relates to hydroelectric turbine installations,and more particularly to a hydraulic turbine with increased powercapacities and a method of refurbishing an existent hydraulic turbine toincrease its power capacities while being fish friendly.

BACKGROUND

Many existing hydroelectric installations are based on Francis turbines,as illustrated in FIG. 1. In these classical installations, the runnerwheel 2 turns in the center of a spiral case 4. A stayring 6 with stayvanes 8 at the outlet of the spiral case 4 guides the water to therunner wheel 2. A radial distributor with wicket gates 10 behind thestay vanes 8 controls the water flow and distributes the water evenlyaround the runner wheel 2. The water passes through the runner wheel 2and follows its course in a draft tube 12.

Such types of installations are often not very fish friendly due to thereduced dimensions of the water passage through the turbine, the speedof the water flow, the water pressure variations across the turbine, theshear in the water flow, etc. The many parts of the turbine which standin the way, like the stay vanes, the wicket gates, possible axial orradial distributors, and the runner wheel, form as many hazards for thefish.

Existing methods of increasing the power of hydraulic turbines generallyconsist of increasing the size of the various parts of theinstallations, which requires more space. Unless spare space is readilyavailable, the power of the existing installations cannot be increasedeasily in this way.

U.S. Pat. No. 1,942,995 (BIGGS); U.S. Pat. No. 3,132,839 (HAEKAL); U.S.Pat. No. 3,305,215 (SWIECICKI et al.); U.S. Pat. No. 3,398,696(SPROULE); U.S. Pat. No. 4,120,602 (MEGNINT); U.S. Pat. No. 4,146,351(KOELLER); U.S. Pat. No. 4,242,289 (BLUM); U.S. Pat. No. 4,575,307(SHINOHARA); U.S. Pat. No. 4,780,051 (FISHER, JR.); U.S, Pat. No.4,867,636 (SAURON et al.); U.S. Pat. No. 5,082,425 (REIL et al.); U.S.Pat. No. 5,261,787 (MORGUNOV); U.S. Pat. No. 5,441,384 (GOKHMAN); U.S.Pat. No. 5,471,965 (KAPICH); U.S. Pat. No. 5,823,740 (CYBULARZ et al.);U.S. Pat. No. 5,879,130 (BEYER et al.); U.S. Pat. No. 5,924,842 (BEYERet al.); U.S. Pat. No. 5,924,844 (CYBULARZ et al.); U.S. Pat. No.5,941,682 (CYBULARZ et al.); U.S. Pat. No. 5,997,242 (HECKER et al.);U.S. Pat. No. 6,036,434 (RAY et al.); U.S. Pat. No. 6,095,749 (BEYER etal.); U.S. Pat. No. 6,114,773 (KOURIS); U.S. Pat. No. 6,152,684 (FERMEet al.); U.S. Pat. No. 6,155,783 (BEYER); U.S. Pat. No. 6,227,798(DEMERS et al.); and U.S. Pat. No. 6,247,893 (BEYER et al.) provideexamples of various other hydraulic turbines and hydroelectricinstallations of the prior art.

SUMMARY

An object of the present invention is to provide a hydraulic turbinewith increased power capacities, which can be used when refurbishingexisting hydraulic turbines or in new hydroelectric installations.

Another object of the present invention is to provide such a hydraulicturbine which retrofit in many existing hydroelectric installations.

Another object of the present invention is to provide such a hydraulicturbine which has a reduced number of blades, vanes and similar parts inthe water passage in comparison with classical turbines, and which isfish friendly at least in this respect.

According to the present invention, there is provided a hydraulicturbine with increased power capacities, comprising:

an axial runner wheel having a rotation axis;

a runner ring peripherally extending around the runner wheel;

a draft tube extending on a downstream side of the runner ring;

a water supply port extending around the rotation axis of the runnerwheel on an upstream side of the runner ring, and adapted to produce asubstantially centripetal water flow swirling around the rotation axisof the runner wheel;

a turning passageway extending between the water supply port and therunner ring, and adapted to guide and redirect the centripetal waterflow in a substantially axial direction of the runner wheel; and

an axial distributor extending between the turning passageway and therunner wheel.

According to the present invention, there is also provided a method ofrefurbishing an existent hydraulic turbine while increasing powercapacities thereof, comprising:

removing any original radial distributor of the existent hydraulicturbine to recover axial space under a water supply port of thehydraulic turbine;

replacing any original stay vanes and wicket gates of the existenthydraulic turbine by new stay vanes having a greater height with respectto the original stay vanes, combined to a reshaping of the water supplyport to accommodate the new stay vanes;

using the recovered axial space to replace an original runner wheel witha larger diameter axial runner wheel combined to a reshaping of a runnerring peripherally extending around the axial runner wheel, the axialrunner wheel and the runner ring being moved downstream with respect toa level of the original runner wheel;

inserting an axial distributor upstream of the axial runner wheel;

reshaping a head of the existent hydraulic turbine to form a turningpassageway between the water supply port and the axial runner wheel,adapted to redirect a centripetal water flow swirling in the watersupply port around a rotation axis of the axial runner wheel in asubstantially axial direction of the axial runner wheel; and

reshaping a draft tube on a downstream side of the runner wheel so thatthe draft tube has an enlarged elbow section with respect to a narroweroriginal elbow section.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of preferred embodiments will be given hereinbelow with reference to the following drawings, in which like numbersrefer to like elements:

FIG. 1 is a cross-section view of a typical Francis turbineinstallation.

FIG. 2 is a cross-section view of a Kaplan turbine installationaccording to the present invention.

FIG. 3 is an enlarged cross-section view of a Kaplan turbine accordingto the present invention.

FIG. 4 is a cross-section view of a propeller turbine installationaccording to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 2, there is shown a hydraulic turbine with increasedpower capacities according to the present invention. The new turbine isintended to be used in installations typically but not restrictivelyoperating under 5 to 60 meters waterfalls with an optimum applicationzone of around 30 meters.

The replacement of a classical turbine by a turbine according to thepresent invention will likely increase the generated power from 50 tomore than 100% while retrofitting in the former structure, thus reducingthe required installation works. In the case of a new electric powerplant, the turbine according to the present invention reduces therequired axial space (or inter-axial space of the groups when severalturbines are used).

In comparison with a classical turbine as shown in FIG. 1, the turbineaccording to the present invention allows to increase the diameter ofthe runner wheel 2′ while keeping the same spiral case 4 and the sameoccupation space in the hydroelectric installation. This increase of therunner wheel's diameter can be achieved as a result of the eliminationof the radial distributor 10. Usually, as a result, the rotation speedof the wheel 2′ is reduced.

The main direction of the water flow through the turbine is depicted byarrows.

In short, the hydraulic turbine according to the present invention hasan axial runner wheel 2′ having a rotation axis 14. A runner ring 34peripherally extends around the runner wheel 2′. A draft tube 12′extends on a downstream side of the runner ring 34. A water supply port42 extends around the rotation axis 14 of the runner wheel 2′ on anupstream side of the runner ring 34. The water supply port 42 isarranged to produce a generally centripetal water flow swirling aroundthe rotation axis 14 of the runner wheel 2′. A turning passageway 16extends between the water supply port 42 and the runner ring 34 to guideand redirect the centripetal water flow in a substantially axialdirection of the runner wheel 2′. An axial distributor 18 extendsbetween the turning passageway 16 and the runner ring 34.

The water supply port 42 can be conveniently provided with a stayring 6′next to the turning passageway 16, and extending above the axialdistributor 18, contrary to the stayring 6 in a typical Francis turbineas shown in FIG. 1.

The stayring 6′ typically has a number of stay vanes 8′ distributedaround the rotation axis 14 of the runner wheel 2′, near the turningpassageway 16. The number of stay vanes 8′ should be chosen according tothe mechanical and hydraulic requirements as explained hereinafter, andmay be reduced to zero in certain cases. As these requirements willoften be lower in the new turbine compared to classical turbine, thenumber of stay vanes 8′ will also often be reduced accordingly, e.g.from 24 to 12.

Stay vanes 8′ having a greater height than usual are preferred in thenew turbine, e.g. a height close to a smallest diameter (or height) ofthe water supply port 42.

Referring to FIG. 3, water is supplied through a penstock (not shown inthe Figures) communicating with the spiral case 4. The spiral case 4 andthe stay vanes 8′ at the water supply port 42 of the spiral case 4 causethe water flow to swirl around the rotation axis 14 of the turbine andto generate a centripetal vortex. The spiral case 4 could be replaced bya water chamber (not shown in the Figures) or any other suitable watersupply structure if desired. The swirling water produces a kineticmomentum. In the meridian plane, the water flow is radial as depicted bythe arrows passing through the stayring 6′, as shown in FIG. 2. The stayvanes 8′ have mechanical and hydraulic functions. The vanes 8′ aresubjected to the mechanical stress of the spiral case 4, the surroundingconcrete and the other mechanical components which press against them.They are also used to correct the direction of the water flow to make ituniform. However, the number of stay vanes 8′ can be reduced to zero incertain configurations.

The water flow follows its course by turning in the meridian plane andexiting from the axial distributor 18 with a direction almost parallelto the rotation axis 14 of the runner wheel 2. The turning of the waterflow before reaching the axial distributor 18 is a particular feature ofthe new turbine.

The axial distributor 18 can be made of a number of adjustable guidevanes, for example 12 to 24, projecting around the rotation axis 14 ofthe runner wheel 2′. Their function is to control the flow betweenstopped and full load operation states with a minimum of losses. Itoperates in a different way from axial guide vanes of classical turbinesby the fact that a very significant kinetic momentum is alreadyinitiated by the upstream components before the turn. The axial guidevanes of classical turbines have a major contribution in the generationof a vortex, which is not the case here. The profile of the guide vanesis thus different in the new turbine. The pitch of the guide vanes canbe horizontal or slightly slanted, ranging for example between 0 to 20degrees or more with respect to a rotation plane 46 of the runner wheel.In the illustrated case, they extend at an angle of 10 degrees withrespect to the horizontal.

The runner wheel 2 is the motor element of the hydraulic turbine. Itspurpose is to transform the power contained in the kinetic momentum ofthe water flow into a torque for a turbine shaft 20 coupled to analternator 22 (as shown in FIG. 2). The turbine can be of a Kaplan typeas illustrated in the Figure, thus with adjustable (tilting) runnerblades 24 extending in a radial plane 46 of the runner wheel 2′ (orslightly inclined with respect to the radial plane 46 if desired), or ofa fixed blade type, e.g. a propeller type of turbine as shown in FIG. 4.

The new turbine can operate in a vertical axis as illustrated, or in ahorizontal or slanted axis.

Referring to FIGS. 1 and 3, the steps for refurbishing an existenthydraulic turbine while increasing its power capacities according to thepresent invention are as follows.

Any increasing of the diameter of the runner wheel 2 in the existentturbine is limited by the wicket gates 10. These wicket gates 10 or anyradial distributor are eliminated in the new turbine as shown in FIG. 3,to recover axial space under the water supply port 42.

The stayring 6 with the stay vanes 8 is replaced by a new stayring 6′with stay vanes 8′ having a greater height for a greater water flow. Theradial space thereby gained is used to increase the diameter of therunner wheel 2 of the new turbine. The water supply port 42 is reshapedto accommodate the new stay vanes 8′.

In the illustrated case, a larger Kaplan runner wheel 2′ is used inreplacement to the original runner wheel 2, which allows to move therunner wheel downstream for the insertion of the axial distributor 18upstream to the runner wheel 2′. The runner ring 34 is also reshapedaccordingly.

The upper wall of the turning passageway 16 can be conveniently formedby the bottom wall of the turbine head cover 48 which is reshapedaccordingly.

From a mechanical standpoint, the mechanisms 26 for controlling theguide vanes 18 require space limited by the bottom pit liner 28 underthe spiral case 4. On the other hand, the mechanical loads transmittedto the stayring 6′ should be transferred to the surrounding concrete.For this purpose, a conical support ring 30 can be used to attach alower lining portion of the spiral case 4 to the stayring 6′ and to thebottom pit liner 28, thereby allowing a transfer of the loads to theconcrete by the bottom pit liner 28 and by the stack formed of the axialdistributor's ring 32, the runner ring 34 and the enlarging dischargering 36. The axial distributor's ring 36 may narrow towards the runnerwheel 2′ to a diameter similar to a diameter of the runner wheel 2′, asshown in FIGS. 2, 3 and 4. The runner ring 34 may likewise narrow asshown in FIGS. 2 and 3 or not, as shown in FIG. 4. The runner wheel 2 ispreferably positioned as close as possible with respect to a guidebearing 38 axially guiding the shaft 20. To this effect, and due to theimportance of the hydraulic patterns, the axis of the guide vanes 18 isslightly slanted as depicted by the dashed lines 40. The upper portionof the draft tube 12′ is also reshaped. The draft tube 12′ is preferablyfurther reshaped with a larger elbow section generally aligned with therotation axis 14 of the runner wheel 2′, followed by a narrower passagecommunicating with the sloped and enlarging section downstream.

The axial distributor 18 may conveniently project around the guidebearing 38.

The increased dimensions of the passages in the new turbine reduce thespeeds, the pressure variations and the shearing effects in the waterflow, which reduces stress on the fish. Also, the reduction in thenumber of blades and vanes in the stayring 6′, the distributor 18 andthe wheel 2′ combined to a reduction in the rotation speed reduce thechances of collisions between the fish and the turbine.

While embodiments of this invention have been illustrated in theaccompanying drawings and described above, it will be evident to thoseskilled in the art that changes and modifications may be made thereinwithout departing from the essence of this invention.

1. A hydraulic turbine with increased power capacities, comprising: anaxial runner wheel having a rotation axis; a runner ring peripherallyextending around the runner wheel; a draft tube extending on adownstream side of the runner ring; a water supply port extending aroundthe rotation axis of the runner wheel on an upstream side of the runnerring, and adapted to produce a substantially centripetal water flowswirling around the rotation axis of the runner wheel; a turningpassageway extending between the water supply port and the runner ring,and adapted to guide and redirect the centripetal water flow in asubstantially axial direction of the runner wheel; an axial distributorextending between the turning passageway and the runner wheels; and abottom pit liner peripherally extending around the axial distributor andthe runner ring; and wherein the water supply port comprises a stay ringnext to the turning passageway and a conical support ring attaching alower part of the water supply port to the stay ring and to the bottompit liner.
 2. The hydraulic turbine according to claim 1, wherein thestay ring extends above the axial distributor.
 3. The hydraulic turbineaccording to claim 1, wherein the stay ring comprises a number of stayvanes distributed around the rotation axis of the runner wheel, near theturning passageway.
 4. The hydraulic turbine according to claim 3,wherein the stay vanes have a height close to a smallest diameter of thewater supply port.
 5. The hydraulic turbine according to claim 3,wherein the number of stay vanes ranges from 12 to
 24. 6. The hydraulicturbine according to claim 1, wherein the axial distributor comprisesadjustable guide vanes projecting around the rotation axis of the runnerwheel.
 7. The hydraulic turbine according to claim 6, wherein the guidevanes have an adjustment pitch range between 0 to 20 degrees withrespect to a rotation plane of the runner wheel.
 8. The hydraulicturbine according to claim 6, wherein the axial distributor furthercomprises means for controlling the guide vanes in a space limited bythe bottom pit liner and a ring of the axial distributor.
 9. Thehydraulic turbine according to claim 1, further comprising a shaftsupporting the runner wheel in the runner ring, and a guide bearingaxially guiding the shaft, the runner wheel extending near the guidebearing.
 10. The hydraulic turbine according to claim 9, wherein theaxial distributor projects around the guide bearing.
 11. The hydraulicturbine according to claim 1, wherein the runner wheel comprises runnerblades slightly inclined with respect to a rotation plane of the runnerwheel.
 12. The hydraulic turbine according to claim 11, wherein therunner wheel is a Kaplan type of wheel.
 13. The hydraulic turbineaccording to claim 1, further comprising a turbine head cover having abottom wall forming an upper wall of the turning passageway.
 14. Thehydraulic turbine according to claim 1, wherein the draft tube has alarge elbow section substantially aligned with the rotation axis of therunner wheel and followed by a narrow passage communicating with asloped and enlarging section.
 15. The hydraulic turbine according toclaim 1, wherein the draft tube has an enlarging discharge ring next tothe runner ring.
 16. The hydraulic turbine according to claim 1, whereinthe axial distributor has a peripheral ring which narrows towards therunner wheel to a diameter substantially similar to a diameter of therunner wheel.
 17. A method of refurbishing an existent hydraulic turbinewhile increasing power capacities thereof, comprising: removing anyoriginal radial distributor of the existent hydraulic turbine to recoveraxial space under a water supply port of the hydraulic turbine;replacing any original stay vanes and wicket gates of the existenthydraulic turbine by new stay vanes having a greater height with respectto the original stay vanes, combined to a reshaping of the water supplyport to accommodate the new stay vanes; using the recovered axial spaceto replace an original runner wheel with a larger diameter axial runnerwheel combined to a reshaping of a runner ring peripherally extendingaround the axial runner wheel, the axial runner wheel and the runnerring being moved downstream with respect to a level of the originalrunner wheel; inserting an axial distributor upstream of the axialrunner wheel; reshaping a head cover of the existent hydraulic turbineto form a turning passageway between the water supply port and the axialrunner wheel, adapted to redirect a centripetal water flow swirling inthe water supply port around a rotation axis of the axial runner wheelin a substantially axial direction of the axial runner wheel; andreshaping a draft tube on a downstream side of the runner wheel so thatthe draft tube has an enlarged elbow section with respect to a narroweroriginal elbow section.
 18. The method according to claim 17, whereinthe hydraulic turbine has a bottom pit liner peripherally extendingaround the axial distributor and the runner ring, and the water supplyport has a stay ring next to the turning passageway, the method furthercomprising: attaching a lower part of the water supply port to the stayring and to the bottom pit liner using a conical support ring.
 19. Themethod according to claim 18, wherein the axial distributor hasadjustable guide vanes projecting around the rotation axis of the axialrunner wheel, the method further comprising: providing means forcontrolling the guide vanes in a space limited by the bottom pit linerand a ring of the axial distributor.